On Wed, 22 May 2013 15:05:44 -0700 Bernie Thompson <bhthompson@xxxxxxxxxxxx> wrote: > On Wed, May 22, 2013 at 2:55 PM, Andrew Morton > <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > > > > On Fri, 10 May 2013 17:53:31 -0700 Bernie Thompson <bhthompson@xxxxxxxxxxxx> wrote: > > > > > This adds in the ability for the rtc sysfs code to handle += characters > > > at the beginning of a wakealarm setting string. This will allow the user to > > > attempt to push out an existing wakealarm by a provided amount. > > > > > > In the case that the += characters are provided but the alarm is not active > > > -EVINVAL is returned. > > > > > > > Well that sounds useful, but I'm not personally in a position to > > confidently judge whether it's useful enough to merge the patch. The > > changelog doesn't make a compelling case and everybody else has chosen > > to sit on their hands. > > > > So I really don't know what to do with this patch. > > > > Thank you for looking at this, I was just talking with Doug on CC this > morning about > explaining why this is useful, at least for my purposes in > suspend/resume testing. > The basic test goes something like: > > 1. Set a wake alarm from userspace 5 seconds in the future > > 2. Start the suspend process (echo mem > /sys/power/state) > > 3. After ~2.5 seconds if userspace is still running (using another > thread to check > this), move the wake alarm 5 more seconds > > If the "move" involves an unset of the wakealarm then there's a > period of time where the system is midway through suspending but has > no wake alarm. It will get stuck. > > We'd rather not remove the "move" since the idea is to avoid a > cancelled suspend when the alarm fires _during_ suspend. It is > difficult for the test to tell the difference between a suspend that > was cancelled because the alarm fired too early and a suspend that was > cancelled/failed for some other reason. OK, I'm (easily) convinced. I guess that if the alarm fires right in the middle of rtc_sysfs_set_wakealarm() execution, everything collapses in a heap. Why does the current code "Avoid accidentally clobbering active alarms"?[*] I'd have thought that being able to reset the expiry time of a pending alarm would be rather useful. [*] repeat after me: comments should explain "what", not "why". grr. -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
